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2018/07/05 21:47:49

David Gibson

TK7 Carburetor

I have TK7 carburetor attached to a Robin trimmer. Problem was, and still is, the fuel siphons out through the carby once the engine is shut down. I have rekitted the carby also replacing the check valve,priming pump, combination valve and needle.
The carby is still flooding. I have tested that the needle is seating, thats ok.
The only other way fuel can get into the chamber is through the return to tank line. I have checked all gaskets and diaphrams aetc are in correctly.
I have been looking at the pump cover to see if fuel can by pass and go back along the return but cannot see any obvious signs.

What have I missed?
Dave

9 comments Leave a comment

AVB

I don't see many Teikei (TK) carburetors used much any more. I would need the model of the Robin trimmer so I can the exploded view of the carburetor.

Meanwhile make sure the metering lever is set correctly. Also the return side check valves that prevent tank pressure from flooding while sitting.

2018/07/06 08:11:53

David Gibson

Thank you for your reply, the Robin trimmer is NB2100A.
I don't know what the metering lever is, I have replaced the combination valve, would that be the return side check valve.
Dave

2018/07/07 21:02:56

AVB

Ahh now I see what you have for a carburetor. I was thinking it was similar to Zama and Walbro carbs that use a metering lever.

About the only thing left is the pump cover being a problem considering what you have already replaced.

2018/07/07 21:26:08

David Gibson

Hi again.
That was my thoughts as well, after carefully studying the operation of the carby, I had a close look at the pump cover,and I put a straight edge along the face when I shone a torch from behind I could see light under the edge were it is supposed to seal the inlet side from the return line.
Also the Priming Pump Plate is bowed as if it has been over tightened, I do not know if that is the way it is meant to be. What do you think?
Dave

2018/07/08 01:39:57

AVB

Normally most times these items are dead flat as go against machined flat surfaces. Over-tightening them can warp them.This area is a compression type fit over the whole area so it must be flat.

This usually done by inexperience trying to use old gaskets. I seldom see it here as most users simply replace the carburetor or throw the trimmer away.

I do however get in carburetors that are so messed up once a while that I definitely know some one didn't know what they were doing. Things missing like screws, screw head stripped out, and mis-ordered gaskets.

2018/07/08 08:47:54

David Gibson

thanks for all your info and tips, I will replace the pump cover, straighten the pump plate and see how that goes.
I would have to agree the time and money I spent might as well throw it away, but it belongs to my neighbor and I enjoy the challenge.
I will let you know how it goes.

Dave

2018/07/09 03:43:45

AVB

If you do this work regularly it might be well worth the extra expense to learn something new.

Currently I have a Shindaiwa 4 stroke hybrid that is driving me crazy but I haven't gave up yet. At first it barely idled. Everything I have tried makes an improvement but it still stalls out at full like it running out fuel. Next project is crankcase seals.

2018/07/09 05:58:31

David Gibson

your right about that, the extra expense will be worth it if it works.

Unfortunately I do not know any thing about your Shinaiwa, I think seals are a good way to go.I have found in the past if the crankcase seals need replacing, it is difficult to start.

2018/07/10 01:51:00

David Gibson

Hi agian.
just returning regarding the TK7 carby. I have replaced the pump body straightened the pump plate. I put the carby back on the trimmer thinking this is the last time all will be good, but it isn't it still floods through the orifice.
I pulled the return line of the pump body and it stops flooding. I will pull the carby off again and have another examination of it to see what else it could possibly be.
Any other ideas out there that might help?

2018/07/29 02:45:05

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TK7 Carburetor

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